textproduct: Albany

WHAT HAS CHANGED

Additional winter storm warnings or winter weather advisories will likely be needed for the lake effect snow that will fall Thursday into Friday. There is also a low to moderate chance for isolated to scattered snow squalls Thursday afternoon.

Finally, confidence remains high for an arctic outbreak Friday night into the weekend. We also added a climate section to show record low and cold high temperatures for January 24 to put into perspective how cold it has been on this date in our climate history but many will likely not reach any records.

We are still monitoring a coastal storm for the second half of the weekend, and recent guidance has trended slightly north with this system.

KEY MESSAGES

1) After a cold start to the morning, attention turns to a clipper system that will bring light to moderate snowfall for areas north of I-90 this afternoon into tomorrow.

2) Confidence continues to increase for dangerously cold temperatures and wind chills Friday night through the weekend. Extreme Cold Weather Warnings and/or Cold Weather Advisories will likely be needed.

3) Moderate confidence that a significant winter storm will impact eastern NY and western New England with at least light to moderate snowfall amounts Sunday into Monday.

DISCUSSION

KEY MESSAGE 1...

An upper trough with several embedded shortwave disturbances tracks over the Great Lakes this afternoon which will help lift a warm front north through the region. With isentropic lift/warm advection, CVA, and increasing low to mid-level moisture, this will result in scattered snow showers developing this afternoon into tonight. With a 50+ kt 850 mb LLJ, there will be quite a bit of terrain influence on the snow, with downsloping into the Hudson Valley, especially from the Capital District southwards, with upslope enhancement in the southern ADKs. Along south- facing slopes in the ADKs, snowfall rates of 1-1.5" per hour will be possible this afternoon and evening per the 00z HREF. A lull in precip will then be possible overnight tonight as we get into the system's warm sector, additional snow showers will redevelop with and ahead of the system's cold front late tonight and Thursday morning. For the foothills of the ADKs, up to 5-9" of snow will be possible, with lower amounts near the CWA border with BTV. Given these snowfall amounts, we have upgraded the existing winter storm watch to an advisory. While a few areas will likely exceed warning criteria (7"), we are not expecting these amounts to be widespread enough to warrant an upgrade to a warning.

As the cold front tracks through the region tomorrow afternoon, some snow squalls may be possible, especially north of I-90 and west of I-87. While convergence along the cold front isn't overly impressive, steepening low-level lapse rates will yield some weak instability, with the Great Lakes acting as a low- level moisture source. Any snow squalls will move through fairly quickly, with this then transitioning to another round of lake effect snow. We opted not to issue any additional headlines for the lake effect at this time given that there are already 2 headlines out. However, with 850 mb temps dropping to -18C over the Lakes, inversion heights increasing to 700-750 mb, and 850 mb winds increasing to 35-40 kt, we will likely see a single band of lake effect snow into northern Herkimer and Hamilton Counties with several additional inches of snow possible Thursday night into Friday. While the rest of the region will remain dry and cold, it will become breezy behind the cold front Thursday afternoon and night. We bumped up wind gusts from the NBM into the 25-35 kt range in collaboration with neighboring offices. Thursday will be fairly mild with highs reaching the 30s to around 40 for many valley areas, but temperatures drop back into the single digits and 10s Thursday night behind the cold front, with the wind making it feel even colder.

KEY MESSAGE 2... Friday, highs will be below normal, only in the 10s to 20s, with mainly dry conditions outside of the lake effect in the ADKs. Then, Friday afternoon or early evening, an arctic cold front will blast through the region as a 496 dam ULL tracks north of our region. This will be by far the coldest airmass of the season, with 850 mb temperatures potentially reaching -30C in the ADKs. With a strong 1050+ mb sfc high building over the northern Plains, the strengthening pressure gradient will result in winds increasing yet again. The combination of very cold temperatures (lows below zero region- wide Friday night) and wind gusts up to 20-30 kt will result in wind chills colder than we have experienced at any point so far this winter. Cold weather advisories and/or extreme cold warnings will likely be needed for much of the region beginning Friday night. Saturday highs will only be in the single digits for valley areas and may very well remain below zero for some of our high terrain areas. Winds diminish Saturday afternoon as the sfc high builds closer from the west, and with this feature overhead Saturday night, low temperatures will likely be similar to if not colder than those Friday night. So, any cold weather/extreme cold headlines would likely run through at least Sunday morning. Temperatures will remain well below normal Sunday, but should rise above cold weather advisory criteria.

The other thing to mention for the Friday afternoon into Saturday timeframe is the potential for some additional lake effect snow. Lake-induced instability looks to reach the extreme classification based on progged 850 mb temps, but low-level flow turns more to the NW behind the arctic front Friday, which will shift any lake bands (likely more multi-bands at this point) more towards the far southwestern Mohawk Valley into the northern Catskills, where additional light accumulations may be possible.

KEY MESSAGE 3... The ensembles and the medium range deterministic guidance continues to trend north and west with a secondary coastal low moving along the Mid Atlantic Coast late Sun/Sun night into Mon producing a widespread accumulating snowfall across the eastern NY and western New England. Initially, arctic high pressure will be over NY and New England Saturday night into Sunday with plenty of frigid air in place. Cold Weather headlines will likely be needed Sat night/Sun for the County Warning Area. An inverted sfc trough associated with with low pressure over the Southeast will focus some snowfall over the region Sun morning into the afternoon. A secondary low forms near the Mid Atlantic Coast late Sun pm/early Sun evening. The primary low decays over the Ohio Valley (associated with the inverted sfc trough), as the secondary coastal low takes over. The track varies on the guidance with some showing a track still well south and east of Long Island and southeast New England, but another cluster is tucked closer to these areas which would mean more snow for the region.

The bottom line is that an extended period of snowfall is supported by the NBM with 30-60% probabilities for snow Sun/Sun night. The latest 24-hr NBM guidance ending 7 am Mon for >4" of snowfall indicates probabilities of 30-60% from the Mohawk Valley/Capital Region/Taconics and Berkshires southward. 24-hr probabilities >6" for the same 24-hr period ending 12Z/Mon are 30-50% from Albany south and east across the region. The snowfall may potentially impact the Monday morning commute. In the mid and upper level deformation zone to the storm system, additional snowfall could continue into Monday afternoon which would add onto the totals. The storm system is still several days out, but confidence is moderate for a light to moderate widespread snowfall with increasing confidence for perhaps a heavy snowfall closer to the I-84 corridor. Snow to liquid ratios look to be above climatological values with an arctic air mass in place, as high temps will be in the single digits to mid teens on Sunday. Lows will be below zero over the southern Dacks and southern Greens Sun night and single digits over the rest of the region. Highs on Mon only recover into the teens and lower 20s, as the snow tapers to flurries and snow showers by the afternoon and night time period.

AVIATION /13Z WEDNESDAY THROUGH SUNDAY/

Through 12Z/Thu...High pressure will move off the NJ Coast this morning with mid and high clouds increasing in the late morning into the early afternoon ahead of a warm front. Flight conditions will be VFR until 18Z-21Z/Wed with some light snow moving into KGFL and then expanding south and east into KALB/KPSF. PROB30 groups were used at KALB/KPSF between 21Z/Wed and 02Z/THU for MVFR conditions. KGFL may be lowering to IFR vsbys by 21Z/Wed and the better chance for IFR conditions for KPSF will be after 02Z/Thu. The clipper associated with the warm front may bring some light snow showers to KPOU after 01Z/Thu with MVFR cigs/vsbys. Widespread low VFR/MVFR cigs are anticipated at all the TAF sites prior to 06Z/Thu. Some improvement to VFR conditions with cigs 3.5-5 kft AGL after 06Z/Thu.

The winds will increase from the southeast to south at 5-10 KT in the late morning, and they will be southerly at 8-12 KT in the afternoon into the early evening with some gusts 20-25 KT at KALB/KPSF. Low Level Wind Shear (LLWS) will become an issue at KGFL/KALB/KPOU/KPSF between 21Z/Wed and 00Z/THU as the sfc winds decrease to less than 10 KT and the 2 kft AGL winds increase to 35-45 KT. LLWS wind shear will continue to about 06Z/Thu before diminishing as the low-level jet moves through.

Outlook...

Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. Breezy. NO SIG WX. Friday Night: Low Operational Impact. Breezy. NO SIG WX. Saturday: Low Operational Impact. Breezy. NO SIG WX. Saturday Night: Low Operational Impact. Slight Chance of SN. Sunday: Moderate Operational Impact. Chance of SN.

CLIMATE

January 24

Record Cold High Temperatures:

Albany, NY: -1 degrees set in 1882 Glens Falls, NY: 0 degrees set in 1907 Poughkeepsie, NY: 8 degrees set in 1948

Record Cold Low Temperatures:

Albany, NY: -17 degrees set in 1948 Glens Falls, NY: -30 degrees set in 2011 Poughkeepsie, NY: -15 degrees set in 1961

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Winter Weather Advisory from 1 PM this afternoon to 1 PM EST Thursday for NYZ032-033-082. MA...None. VT...None.